Process for producing microcoils and microtransformers

Abstract

A process for producing single-layer or multi-layer microcoils or microcoil arrays that optionally have a magnetic core area to increase the coil inductance and to guide the magnetic flux. In this process, plastic films (e.g., made of polyimide or polyester), are applied using pressure and heat to serve as the insulation layers. This eliminates the need for curing the insulation and expensive leveling operations.

What is claimed is: 
     
       1. A method for producing microcoils having at least one coil winding, comprising the steps of: (a) applying a conducting primer layer to one side of an insulating substrate;   (b) applying a structurable layer to the conducting primer layer;   (c) structuring the structurable layer to form a mold for a coil winding;   (d) filling the mold with a material for the coil winding;   (e) removing the structurable layer; and   (f) applying, via a leveling process, an insulating layer of plastic film having an adhesive layer over the coil winding.   
     
     
       2. The method according to claim 1, wherein the plastic film includes one of polyimide and polyester. 
     
     
       3. . The method according to claim 1, wherein the insulating layer of plastic film is applied by pressure and heat. 
     
     
       4. The method according to claim 1, wherein the coil winding is designed as a double coil winding. 
     
     
       5. The method according to claim 1, wherein the structurable layer includes a positive lacquer. 
     
     
       6. The method according to claim 1, wherein a material for the coil winding includes one of Cu, Ag and Au. 
     
     
       7. The method according to claim 1, further comprising the step of: (g) repeating steps (a) through (f) for each additional coil winding, so that the coil windings have a stacked configuration.   
     
     
       8. The method according to claim 7, further comprising the step of, after applying the insulating layer of plastic film: introducing a plated-through hole in the layer of plastic film by forming a contacting hole in the insulating layer, the plated-through hole extending to the coil winding underneath and being filled with the material for the coil winding.   
     
     
       9. The method according to claim 1, wherein the layer of plastic film is provided with a metal layer, the metal layer functioning as one of a conducting primer layer and an etching mask on a side of the coil winding facing away from a surface to be leveled. 
     
     
       10. A method for producing microcoils having at least one coil winding, comprising the steps of: (a) producing a magnetic core bottom part on one side of an insulating substrate;   (b) covering the magnetic core bottom part with an insulation layer;   (c) applying a conducting primer layer on the insulation layer;   (d) applying a structurable layer to the conducting primer layer;   (e) structuring the structurable layer to form a mold for a coil winding;   (f) filling the mold with a material for the coil winding;   (g) removing the structurable layer;   (h) applying, via a leveling process, an insulating layer of plastic film having an adhesive layer over the coil winding;   (i) repeating steps (c) through (g) for each additional coil winding, so that the coil windings have a stacked configuration;   (j) forming a first recess in a core area surrounded by the coil windings and forming a second recess in a surrounding magnetic core area surrounding the coil windings, the first and second recesses extending through the insulating layer of plastic film of each coil winding and through the insulation layer of the magnetic core bottom part;   (k) filling the first and second recesses with a magnetic material; and   (l) forming a magnetic core top part connecting the core area and the surrounding magnetic core area, wherein the core area and the surrounding magnetic core area are connected to the magnetic core bottom part.   
     
     
       11. The method according to claim 10, wherein the magnetic material includes FeNi. 
     
     
       12. The method according to claim 10, wherein the magnetic material includes one of a ternary alloy and a quaternary alloy. 
     
     
       13. The method according to claim 10, wherein the magnetic material includes a hard magnetic powder dispersed in a polymer. 
     
     
       14. The method according to claim 10, wherein at least one of the first and second recesses is filled with a predetermined magnetic insulation material to create specific flux paths. 
     
     
       15. The method according to claim 10, wherein the coil windings are made of one of Cu, Ag and Au.